Design Decisions: Finding an Alternative Military Battery

While the battery chemistries used to power single-use military and aerospace applications remained virtually unchanged for decades, technological advancements have pushed legacy batteries to their limit in terms of supporting advanced product designs for avionics, navigation systems, ordinance fuses, missile systems, GPS tracking and emergency/safety devices, shipboard, and oceanographic devices.

Recognizing that antiquated battery technologies would hold back new product development, the US Department of Defense identified the “critical need” for a new generation of high-power, long-life batteries for single-use applications. From this challenge, a new battery technology has emerged that represents a viable alternative to legacy battery technologies.

Reserve and thermal batteries store the electrolyte separately from other active ingredients, which keeps it inert until a pyrotechnic device initiates a chemical reaction. The most popular type of reserve battery is the thermal battery, which utilizes a metallic salt electrolyte that is inert and non-conducting in its solid state at ambient temperatures. A squib delivers a pyrotechnic charge that causes the electrolyte to become molten at 400C to 700C, thus energizing the cell to deliver short-term continuous current from a few watts to several kilowatts depending upon battery size and chemistry.

Advantages of thermal battery design include ruggedness, safety, reliability, and long shelf life. Limitations include an inability to test the cell without fully depleting it, delayed battery activation, and the need for insulation layers to keep the molten electrolyte at a steady temperature, and to protect surrounding components from heat-related damage.

I know this battery technology isn't the same as the lithium ion batteries that the automotive industry is consumed with trying to find the best solution for EV vehicles. However, the thought occurs to me that there has to be synergies/best practices each side could bring to each other to advance innovation and future battery development. I'm wondering if there are open source communities or standards bodies promoting cross-pollination of ideas or research. Clearly advancing the cause of alternative battery design has huge implications, not just for the EV set.

I think such military technologies have to go for mass production in sake of public. We all are experienced energy crunch in our daily life at different instances in portable devices like Smartphone, Camera, laptops etc. So such long durability cells can yield more power for a long duration. By sharing such technologies to the public, I don't think there may be any security issues.

I had the same thought as Beth: there might be some crossover apps possible from military uses to civilian uses, since there are a lot of parallels. Battery technologies have lagged for so many years, if not decades. It's great to see the military spearheading efforts to take a crack at improvements. It's also interesting to see thermal storage battery techniques--I just read something about thermal storage applied to solar energy.

Does anybody know what the technical reasons are for the the differences between military and cilivian uses? Obviously, there are the harsh environment considerations, but I never realized there was such an underlying difference in basic technology.

Jack, military everything has to be more rugged and last longer--a lot longer. It also has to be fixable on the spot if at all possible. (That last probably doesn't apply to batteries.) Military vehicles now carry a ton of electronics and other stuff that needs to be powered, as mentioned in the first paragraph: advanced product designs for avionics, navigation systems, ordinance fuses, missile systems, GPS tracking and emergency/safety devices, shipboard, and oceanographic devices.

What I'd like to know is how "single-use" is defined as applied to batteries.

On single use & military vs. civilian: Military applications cited appear to require shelf life of years to decades (presumabily in severe environmental conditons followed by total lifetimes of minutes to hours, possibily at extreme pulse currents and/or physical contitions, with extremely high reliability.

Civilian uses tend to have somewhat less severe storage life requirements, e.g. less that 1 decade, and longer duration (hours to years), less severe discharge requirements for primary (i.e. non-rechargable) battery systems, in far less severe environmental conditions.

Stephen, thanks for the definitions. I understand the contrasts between the military and consumer usage scenarios you mention, but how they apply to batteries wasn't clear; now it is. So it sounds like batteries have to stand up to this extreme "wait and hurry up" model.

From the article, I didn't get a good appreciation for the Silver-Zinc batteries. It seemed like only the limitations prevailed. I'm wondering about the advantages of this technology and what specific application it should be used in.

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